It has been desirable to improve the color rendition of photographic elements. More specifically, it is desirable to have the ability to inhibit the red- and the blue- sensitive layers to the desired degree as a function of green layer development.
One method for improved color reproduction is through the use of colored couplers as described in U.S. Pat. Nos. 4,163,670; 2,428,054; and 3,148,062. However, with this method of color correction, the nonexposed areas are highly colored which can lead to long printing times. Furthermore, in a multilayer structure where the layer arrangement is blue-sensitive, green-sensitive, and red-sensitive, with respect to the exposing light only a yellow colored coupler could be used in the green-sensitive layers or there would be a loss in red layer sensitivity.
The use of "DIR couplers" or "development inhibitor releasing" couplers as defined in C. R. Barr, J. R. Thirtle, and P. W. Vittum, Photographic Science and Engineering, Vol. 13, 74N, 80 214-217 (1969),are generally known to provide interlayer effects and improve color reproduction through the imagewise release of inhibitor fragments. There are generally two types of inhibitor fragments: inhibitor fragments which strongly adsorb to silver and greatly suppress development (strong inhibitors) and inhibitor fragments which weakly adsorb to silver and suppress development to a lesser degree (weak inhibitors). Both types of inhibitor fragments can be linked to the coupler through a timing group which allows the inhibitor precursor to diffuse. However, DIRs linked through a timing group to a pyrazolone nucleus are unstable and costly to manufacture. Therefore, there is a need to have DIR compounds in the green sensitive layers which overcome the existing deficiencies.
There have been numerous attempts to define layer arrangements incorporating DIRs of various types. For example, U.S. Pat. No. 4,804,619 discloses the use of diffusible DIRs in a highest green-sensitive layer of a specified layer thickness. The inhibitor fragment released from the DIR may be diffusible because of its weak inhibiting ability or may be linked through a timing group to permit it to diffuse. However, no particular combination of DIRs to be used in the fast and in the slower layers is disclosed.
U.S. Pat. No. 4,414,308 teaches the inclusion of a DIR with a timing group in the fast, the slow and/or an intermediate nonsensitive layer of a multilayer pack. No particular arrangement of layers nor combination of DIRs is suggested.
Other U.S. patents that deal with the use of DIRs in multilayer applications are the following: U.S. Pat. Nos. 4,963,465; 4,145,219; 4,273,861; 4,670,375; and 4,564,587. None of the disclosed arrangements provide the desired effect of green light on the red and blue records so as to improve the color rendition sufficiently.
It is therefore a problem to be solved to provide a photographic element and process which provide improved color rendition through the ability to inhibit the red- and blue-sensitive layers to the desired degree as a function of the development of the green-sensitive layers through the incorporation of a specified combination of DIRs.